The first athletes have checked into Beijing's newly-built Olympic village, with 12 days to go until the Games.
China's basketball star Yao Ming and hurdler Liu Xiang were present for a flag-raising ceremony at the heavily guarded site.
The opening came on a muggy morning and correspondents reported a haze of pollution over the village's complex of luxurious, high-rise apartments.
In all 16,000 competitors will stay there during the games.
The BBC's Quentin Sommerville, in Beijing, says the flats - housing either four or eight people each - have been built to an unusually high environmental standard for China.
Solar energy will power some of the buildings, and unlike most of China, residents will be able to drink the water straight from the tap.
Specially extended beds have been installed for taller athletes.
Food safety is a concern in China, so everything served to the athletes will have undergone spot checks at mobile laboratories, our correspondent says.
Key to the village
Speaking at the opening ceremony, a vice-president of Beijing's organising committee, Chen Zhili, said: "We now welcome athletes from around the world to come to the Games."
Chen, the so-called mayor of the village, added: "We will try to satisfy the needs of people from different cultural and religious backgrounds."
He received a symbolic gold key to the village from organizing committee president Liu Qi, also the head of Beijing's Communist Party.
Chinese athletes were the first to check into the village.
The flats will be refitted and sold after the Olympics.
Reports say they will cost up to $1m (£500,000) - considered a high price even in Beijing's soaring property market.